A group of electrical receptacles is referred to as “protective” receptacles because some measure has been taken in the construction to protect children and others from harm if they should intentionally or inadvertently insert or attempt to insert an electrically conductive article into the electrically energized portions of the receptacle. Conventional electrical receptacles have a nonconductive face portion with openings to receive plug blades. In normal use, the blades pass through the nonconductive space and are received by conductive female elements that are connected to line voltage. A child inserting, for example, a paper clip or the conductive portion of a toy into the energized conductive elements can be seriously injured.
To avoid this danger, “shuttered” receptacles resist insertion and electrical connection of anything other than the blades of an appropriate plug by elements provided between the faceplate and the conductive elements. The electrical energization of internal components is not controlled; rather, access to those conductive elements is prevented except under a defined set of circumstances.
An example of a shuttered receptacle is found in U.S. Pat. No. 4,379,607 to Bowden, Jr. (the Bowden '607 patent), the subject matter of which is hereby incorporated by reference. The Bowden '607 patent discloses two identical slideable shutter members 56 provided behind the slots 70 in the cover 54 and in front of the terminals 68 within the receptacle base 52, as shown in FIGS. 1, 2 and 7. Each of the two identical shutter members has a cam surface 108 and a blocking portion 106. The cam surfaces 108 are positioned so that each one is contacted by a blade and is caused to move so that its blocking portion unblocks the slot for the other blade. Thus, when the two blades are concurrently inserted, they act against the two cam surfaces and unblock each other's passageways.
However, the Bowden '607 patent requires two shutter members to properly provide tamper resistance to the electrical receptacle. Thus, a need exists for an improved tamper resistant assembly in which one shutter member provides tamper resistance for an electrical receptacle, thereby reducing inventory and costs.
Furthermore, a shutter member that is limited to linear motion is resistant to actuation upon insertion of a plug blade. Therefore, a need exists for a shutter member that moves in two dimensions to increase the responsiveness of the shutter member to inserted plug blades, thereby providing a more efficient tamper resistant assembly.
Thus, there is a continuing need to provide improved tamper resistant assemblies for electrical receptacles.